The research proposed in this application will continue the biochemical characterization of membranes in normal and leukemic lymphocytes. Previous studies, which showed heterogeneity for 5' nucleotidase (5'N) in cells from patients with chronic lymphocytic leukemia will be extended to establish the following: 1) Whether the lack of activity is caused by the absence of protein or a functionally impaired molecule; 2) The genetic control of 5'N; 3) The relationship (if any) between the lack of 5'N activity and other membrane enzymes' activities; 4) The effect of infection with E-B virus on 5'N activity. These studies will be conducted on the cells isolated from patients and in tissue culture. Biochemical, immunologic and histochemical methods will be used. The enzyme will be purified to homogeneity and an antibody prepared. It will be established whether a cross-reactive material exists in 5'N negative cells. Family studies will determine if low and high 5'N kindreds exists. The histochemical assay will be used to investigate whether normal lymphocytes consist of 5'N positive and negative subpopulations. The activity of several membrane enzymes in the same pathway will be quantitated in order to establish whether the decreased 5'N is associated with other deficiencies.